A smooth picture is your reward for carrying a 4x5 camera in an awkward case out into the field. Now the OP was inquiring on how to get less grain in his pictures, not whether or not it should be there.
That is exactly right, and he was made to feel bad by folks who insist that we should just accept grain. I respect the right of those persons to make prints with golf ball size if they like. Why won't they accept that others of us have the right to seek toi eliminate or minimize grain in our work if we so choose? What is up with folks who want to impose their aesthetic principles on the rest of us?
Sandy King
